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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 08:50:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 08:50:16 -0700
commit39a5101f989e8d2be557136704d53990f9b402c8 (patch)
treeb9c16c6f32508939111fb6d0159d7450713a5f33 /lib/mpi/mpi-mod.c
parent865c50e1d279671728c2936cb7680eb89355eeea (diff)
parent3093e7c16e12d729c325adb3c53dde7308cefbd8 (diff)
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Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto updates from Herbert Xu: "API: - Allow DRBG testing through user-space af_alg - Add tcrypt speed testing support for keyed hashes - Add type-safe init/exit hooks for ahash Algorithms: - Mark arc4 as obsolete and pending for future removal - Mark anubis, khazad, sead and tea as obsolete - Improve boot-time xor benchmark - Add OSCCA SM2 asymmetric cipher algorithm and use it for integrity Drivers: - Fixes and enhancement for XTS in caam - Add support for XIP8001B hwrng in xiphera-trng - Add RNG and hash support in sun8i-ce/sun8i-ss - Allow imx-rngc to be used by kernel entropy pool - Use crypto engine in omap-sham - Add support for Ingenic X1830 with ingenic" * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (205 commits) X.509: Fix modular build of public_key_sm2 crypto: xor - Remove unused variable count in do_xor_speed X.509: fix error return value on the failed path crypto: bcm - Verify GCM/CCM key length in setkey crypto: qat - drop input parameter from adf_enable_aer() crypto: qat - fix function parameters descriptions crypto: atmel-tdes - use semicolons rather than commas to separate statements crypto: drivers - use semicolons rather than commas to separate statements hwrng: mxc-rnga - use semicolons rather than commas to separate statements hwrng: iproc-rng200 - use semicolons rather than commas to separate statements hwrng: stm32 - use semicolons rather than commas to separate statements crypto: xor - use ktime for template benchmarking crypto: xor - defer load time benchmark to a later time crypto: hisilicon/zip - fix the uninitalized 'curr_qm_qp_num' crypto: hisilicon/zip - fix the return value when device is busy crypto: hisilicon/zip - fix zero length input in GZIP decompress crypto: hisilicon/zip - fix the uncleared debug registers lib/mpi: Fix unused variable warnings crypto: x86/poly1305 - Remove assignments with no effect hwrng: npcm - modify readl to readb ...
Diffstat (limited to 'lib/mpi/mpi-mod.c')
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+/* mpi-mod.c - Modular reduction
+ * Copyright (C) 1998, 1999, 2001, 2002, 2003,
+ * 2007 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ */
+
+
+#include "mpi-internal.h"
+#include "longlong.h"
+
+/* Context used with Barrett reduction. */
+struct barrett_ctx_s {
+ MPI m; /* The modulus - may not be modified. */
+ int m_copied; /* If true, M needs to be released. */
+ int k;
+ MPI y;
+ MPI r1; /* Helper MPI. */
+ MPI r2; /* Helper MPI. */
+ MPI r3; /* Helper MPI allocated on demand. */
+};
+
+
+
+void mpi_mod(MPI rem, MPI dividend, MPI divisor)
+{
+ mpi_fdiv_r(rem, dividend, divisor);
+}
+
+/* This function returns a new context for Barrett based operations on
+ * the modulus M. This context needs to be released using
+ * _gcry_mpi_barrett_free. If COPY is true M will be transferred to
+ * the context and the user may change M. If COPY is false, M may not
+ * be changed until gcry_mpi_barrett_free has been called.
+ */
+mpi_barrett_t mpi_barrett_init(MPI m, int copy)
+{
+ mpi_barrett_t ctx;
+ MPI tmp;
+
+ mpi_normalize(m);
+ ctx = kcalloc(1, sizeof(*ctx), GFP_KERNEL);
+
+ if (copy) {
+ ctx->m = mpi_copy(m);
+ ctx->m_copied = 1;
+ } else
+ ctx->m = m;
+
+ ctx->k = mpi_get_nlimbs(m);
+ tmp = mpi_alloc(ctx->k + 1);
+
+ /* Barrett precalculation: y = floor(b^(2k) / m). */
+ mpi_set_ui(tmp, 1);
+ mpi_lshift_limbs(tmp, 2 * ctx->k);
+ mpi_fdiv_q(tmp, tmp, m);
+
+ ctx->y = tmp;
+ ctx->r1 = mpi_alloc(2 * ctx->k + 1);
+ ctx->r2 = mpi_alloc(2 * ctx->k + 1);
+
+ return ctx;
+}
+
+void mpi_barrett_free(mpi_barrett_t ctx)
+{
+ if (ctx) {
+ mpi_free(ctx->y);
+ mpi_free(ctx->r1);
+ mpi_free(ctx->r2);
+ if (ctx->r3)
+ mpi_free(ctx->r3);
+ if (ctx->m_copied)
+ mpi_free(ctx->m);
+ kfree(ctx);
+ }
+}
+
+
+/* R = X mod M
+ *
+ * Using Barrett reduction. Before using this function
+ * _gcry_mpi_barrett_init must have been called to do the
+ * precalculations. CTX is the context created by this precalculation
+ * and also conveys M. If the Barret reduction could no be done a
+ * straightforward reduction method is used.
+ *
+ * We assume that these conditions are met:
+ * Input: x =(x_2k-1 ...x_0)_b
+ * m =(m_k-1 ....m_0)_b with m_k-1 != 0
+ * Output: r = x mod m
+ */
+void mpi_mod_barrett(MPI r, MPI x, mpi_barrett_t ctx)
+{
+ MPI m = ctx->m;
+ int k = ctx->k;
+ MPI y = ctx->y;
+ MPI r1 = ctx->r1;
+ MPI r2 = ctx->r2;
+ int sign;
+
+ mpi_normalize(x);
+ if (mpi_get_nlimbs(x) > 2*k) {
+ mpi_mod(r, x, m);
+ return;
+ }
+
+ sign = x->sign;
+ x->sign = 0;
+
+ /* 1. q1 = floor( x / b^k-1)
+ * q2 = q1 * y
+ * q3 = floor( q2 / b^k+1 )
+ * Actually, we don't need qx, we can work direct on r2
+ */
+ mpi_set(r2, x);
+ mpi_rshift_limbs(r2, k-1);
+ mpi_mul(r2, r2, y);
+ mpi_rshift_limbs(r2, k+1);
+
+ /* 2. r1 = x mod b^k+1
+ * r2 = q3 * m mod b^k+1
+ * r = r1 - r2
+ * 3. if r < 0 then r = r + b^k+1
+ */
+ mpi_set(r1, x);
+ if (r1->nlimbs > k+1) /* Quick modulo operation. */
+ r1->nlimbs = k+1;
+ mpi_mul(r2, r2, m);
+ if (r2->nlimbs > k+1) /* Quick modulo operation. */
+ r2->nlimbs = k+1;
+ mpi_sub(r, r1, r2);
+
+ if (mpi_has_sign(r)) {
+ if (!ctx->r3) {
+ ctx->r3 = mpi_alloc(k + 2);
+ mpi_set_ui(ctx->r3, 1);
+ mpi_lshift_limbs(ctx->r3, k + 1);
+ }
+ mpi_add(r, r, ctx->r3);
+ }
+
+ /* 4. while r >= m do r = r - m */
+ while (mpi_cmp(r, m) >= 0)
+ mpi_sub(r, r, m);
+
+ x->sign = sign;
+}
+
+
+void mpi_mul_barrett(MPI w, MPI u, MPI v, mpi_barrett_t ctx)
+{
+ mpi_mul(w, u, v);
+ mpi_mod_barrett(w, w, ctx);
+}